<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>hello world</title>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>

<body>
    <div id="demo">{{ fullName }}</div>


    <div id="watch-example">
        <p>
            Ask a yes/no question:
            <input v-model="question">
        </p>
        <p>{{ answer }}</p>
    </div>


    <div id="class" class="static" v-bind:class="{ active: isActive, 'text-danger': hasError }">sss
        <div v-bind:class="classObject">aaa</div>
    </div>
</body>
<script>

    var cls = new Vue({
        el: "#class",
        data: {
            isActive: true,
            hasError: false,
            error: null,
            classObject: {
                active: true,
                'text-danger': false
            }
        },
        computed: {
            classObject: function () {
                return {
                    active: this.isActive && !this.error,
                    'text-danger': this.error && this.error.type === 'fatal'
                }
            }
        }
    })
    // var vm = new Vue({
    //     el: '#demo',
    //     data: {
    //         firstName: 'Foo',
    //         lastName: 'Bar',
    //         fullName: 'Foo Bar'
    //     },
    //      //侦听属性
    //     watch: {
    //         firstName: function (val) {
    //             this.fullName = val + ' ' + this.lastName
    //         },
    //         lastName: function (val) {
    //             this.fullName = this.firstName + ' ' + val
    //         }
    //     }
    // })


    var vm = new Vue({
        el: '#demo',
        data: {
            firstName: 'Foo',
            lastName: 'Bar'
        },
        // computed: {
        //     // 计算属性的 getter
        //     fullName: function () {
        //         // `this` 指向 vm 实例
        //         return this.firstName + ' ' + this.lastName
        //     }
        // }
        computed: {
            fullName: {
                // getter
                get: function () {
                    return this.firstName + ' ' + this.lastName
                },
                // setter
                set: function (newValue) {
                    var names = newValue.split(' ')
                    this.firstName = names[0]
                    this.lastName = names[names.length - 1]
                }
            }
        }
    })

</script>


<!-- 因为 AJAX 库和通用工具的生态已经相当丰富，Vue 核心代码没有重复 -->
<!-- 提供这些功能以保持精简。这也可以让你自由选择自己更熟悉的工具。 -->
<script src="https://cdn.jsdelivr.net/npm/axios@0.12.0/dist/axios.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/lodash@4.13.1/lodash.min.js"></script>
<script>
    var watchExampleVM = new Vue({
        el: '#watch-example',
        data: {
            question: '',
            answer: 'I cannot give you an answer until you ask a question!'
        },
        watch: {
            // 如果 `question` 发生改变，这个函数就会运行
            question: function (newQuestion, oldQuestion) {
                this.answer = 'Waiting for you to stop typing...'
                this.debouncedGetAnswer()
            }
        },
        created: function () {
            // `_.debounce` 是一个通过 Lodash 限制操作频率的函数。
            // 在这个例子中，我们希望限制访问 yesno.wtf/api 的频率
            // AJAX 请求直到用户输入完毕才会发出。想要了解更多关于
            // `_.debounce` 函数 (及其近亲 `_.throttle`) 的知识，
            // 请参考：https://lodash.com/docs#debounce
            this.debouncedGetAnswer = _.debounce(this.getAnswer, 500)
        },
        methods: {
            getAnswer: function () {
                if (this.question.indexOf('?') === -1) {
                    this.answer = 'Questions usually contain a question mark. ;-)'
                    return
                }
                this.answer = 'Thinking...'
                var vm = this
                axios.get('https://yesno.wtf/api')
                    .then(function (response) {
                        vm.answer = _.capitalize(response.data.answer)
                    })
                    .catch(function (error) {
                        vm.answer = 'Error! Could not reach the API. ' + error
                    })
            }
        }
    })
</script>

</html>